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Determine the equilibrium pH of aqueous solutions for the following strong acids

  • Thread starter tobyracine
  • Start date
  • #1
Determine the equilibrium pH of aqueous solutions for the following strong acids or bases: (a) 257mg/L of HSO4- ; (b) 10nM NaOH ; (c) 75ug/L of HNO3
 

Answers and Replies

  • #2
AGNuke
Gold Member
455
9
Look for their respective Ka values on net.
 
  • #3
I kind of figured it out except for the first one, because HSO4- can become an acid or a base depending what it's mixed with so I don't know what to do, do I get the pH or the pOH? And how?
 
  • #5
Thanks
 
  • #6
148
2
Not totally relevant to the OP, but part (b) of this exercise is nonsensical in any practical terms. I bring this up because we are in the "Chemistry" forum rather than the "Chemistry Homework" forum.

The answer to a formal calculation to part (b) will only bear any relationship to reality if the concentration of carbon dioxide/bicarbonate in the water is much smaller than that of the hydroxyl -- say 1 nM or less. Any normal aqueous solution will be acting as a carbonate buffer for such low levels of hydroxyl, and I would like to know how anyone proposes to prepare a water sample that is accessible for normal laboratory work, but less than 1 nM in bicarbonate/carbon dioxide.
 
  • #7
Borek
Mentor
28,296
2,681
It is a typical trick question asked every year :smile:

And heck, you are right about homework... Moving the thread.

toby: please read forum rules.
 

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